Isaac Newton’s second Law of Motion states that, Force = Mass x Acceleration. For this project I intend to prove or disprove this theory. The fact that the Law has survived 300 years of evolving science provides much of the needed evidence that the Law is truthful and works but I will do the experiment to determine my own set of results.
I hope to answer the question:
‘Is there a link between mass and acceleration ?’
Newton’s Second Law
Newton’s Second Law is a way of finding the force that is acting on a certain object by using the known mass of the object and the projected acceleration and that the mass is inversely proportional to the acceleration.
For example, A bus keeps going forward because the forces of acceleration and friction are unbalanced but as soon as these forces become balanced than the bus will keep a steady speed. It is this that I am going to investigate.
The Law can be tested quite easily by using a simple test, involving a trolley, a ramp and some weights. The experiment is explained below.
I will be using Force as the input variable for this experiment. I will change the force with which the trolley will be pulled down the ramp with and will see what affect this has on the acceleration.
I will be measuring the accelleration of the trolley as it runs down the ramp. I will compare this to the mass and then I will see if there is any connection and if the law does actually work.
The object I intend to use as the mass is a three-wheeled trolley. I will measure the trolleys mass before using it in the experiment. I will use a 2 metre long runway to measure the acceleration of the trolley. The runway will be slightly elevated so that the amount of friction that is acting on the trolley will be at a minimum. To combat the friction when the string and weights are pulling the trolley down the ramp, I will use a pulley to make sure as little friction as possible will occur. I will also have the ramp at an angle which will produce as little friction as possible. This is important because if I didn’t do this then the friction that would occur would slow down the trolley and I would get anomalous results. I will use differing amounts of weights to pull the trolley down the runway. We are planning to do 5 experiments, each with a different force. The first will have a resultant force of 1 Newton, the second will have a force of 2 Newton’s and so on. To measure the rate of acceleration we will use a ticker timer. This will record accurately the increase in velocity and then using either 5 or 10 tick lengths we can work out the recorded acceleration and compare it to the projected acceleration that we have worked out using Newton’s second Law. The experiment will be set up as shown below
Ticker Timer Ticker Tape Trolley Ramp Pulley
I think that this is the best way to perform this experiment because if you did it, as some of the class did, by pulling the trolley using a force meter, then it would be quite difficult to pull the trolley at a steady force and so would not get such accurate readings.
To work out the results I will use the formula, Acceleration = Force A= F
Output = Input
It is easier for a smaller, lighter object to be moved rather than a larger heavier object. For a small object, with a smaller mass to accelerate at the same speed as a larger object with a larger mass, the force would need to be increased with the size of the object. In this experiment, though, the force will be constant, as the variable being changed is ‘mass’, therefore, the acceleration will decrease as the mass increases.
A list of the equipment I will need is shown below:
1. A Trolley
2. A Two Metre long ramp
3. A Ticker Timer
4. Ticker Tape
5. A Pulley – so when we let the weights drop there will be as little friction as possible.
7. 5x 1Newton weights
We will measure the acceleration caused by a certain weight three times to make sure we get the right results.
See page one for variables being tested.
How to make it a fair test
To make the experiment fair, the only variable that I will change is the amount of weight that is used to pull the trolley down the runway. All the other components i.e. length of string, height of runway, and stated variables will be kept the same.
Based on the results that we obtained when we used Newtons Theory to work out the projected accelerations for each different weight, I would say that the more weight that is applied to pull the trolley down the ramp the more the trolley will accelerate. This is because the trolley has an unbalanced force which means it will accelerate. The object will continue to accelerate until the forces (gravity and friction) are balanced at which time it will keep travelling at a constant force (speed) until the forces become unbalanced again which will make the trolley slow down.
Following the theory that ‘ the mass is inversely proportional to the acceleration’, I predict that when all the results have been calculated, and placed on a graph, it will look similar to the following:
As the mass increases, the
Acceleration increases and as the
Mass decreases, the acceleration
When performing the experiments there are going to be a lot of loose wires from the ticker timer, the power pack etc. I will have to make sure that these are kept well out of the way and will not harm anyone. The use of weights could be a hazard so they will have to be handled properly and not thrown or dropped anywhere near peoples feet or hands. Because we are using a 2 metre long ramp, it will be too long to fit on a desk, I will have to find a suitable place to put this otherwise people will hurt themselves on the protruding end of it.
This is a table of my groups results
Recorded Acceleration (m/s/s )
My results are highlighted in red
Below is a graph of my results. I have used averages of the 3 recorded acceleration in the graph.